The next logical step in getting the machine up seemed to be going through the wiring harnesses, so I spent some time stripping them all completely out of the machine (and taking pictures each step of the way so I’ll hopefully remember how to put them back). Pulling everything out also means the chassis itself… Continue Reading →
I’d reversed enough of the PSU’s linear board to generally understand what was going on with it, so figured it was time to start trying to power things up bit by bit. Starting out with everything except the transformer disconnected and the system connected through a current limiting bulb and variac, I brought the voltage… Continue Reading →
I’m still working on reversing the PSU linear board into a schematic (making good progress and learning a lot), but the next physical step will be to start bringing up the linear part of the power supply. To do this, I want to be able to limit the amount of current it can draw at… Continue Reading →
I’m waiting on a variac I’m borrowing from another lab member before I can start bringing up the PSU, so I started reverse engineering the linear board of the power supply into a schematic this evening. This is partly to help with any required troubleshooting, and partly (mostly) since I want to understand how it… Continue Reading →
Got more or less all the pins on all the connectors traced on the linear board of the power supply this evening! There are convenient test points on the front of the unit for all the voltage rails, which made tracing which pin on which connector much easier than it might have otherwise been. A… Continue Reading →
Started looking over the power supply tonight, since that’s the logical first part to power up. Ever since I’d first opened the system’s case I’d wondered why there was both a power supply box as well as a giant transformer in the unit. It turns out that the transformer is part of the power supply,… Continue Reading →
The Dandelion has a small panel on the front under a flip-down cover for performing maintenance and diagnostics on the system. There’s a dedicated PCB behind it that provides some diagnostic output via 7-segment displays, pushbutton inputs to control the boot process, and some RTC clocking circuits. This seemed like a good place to start… Continue Reading →
Since the Dandelion was sitting in a garage for years before I got it, there’s a lot of rust on many of the parts. As we moved it into its new home, rust was falling off of the bottom fan cover all over the place, so the first priority was taking care of that to… Continue Reading →
About a decade ago I got a Xerox Star 8010 (Dandelion) from a friend of a friend. It had been stored in a garage and was all rusty, and had previously had mice living inside it who used the insulation from various wiring harnesses to make a nest. I’d been storing it with the eventual… Continue Reading →